In mobile telecommunication networks, when User Equipment (UE) wants to send data to or receive data from the network, the network initially sends configuration data to the UE so that it can communicate with the network using the correct parameters. The configuration data includes, among other things, when the UE should start to cipher the uplink data it sends to the network (Activation Time). In response to receiving the configuration data, the UE configures its internal resources accordingly and sends a message back to the network confirming that the configuration was successful. The network then starts to cipher downlink data after receiving this confirmation message. However, in practice, this confirmation message may not be sent until after the Activation Time and in this case, any uplink data sent from the UE to the network or downlink data sent from the network to the UE, before the network has received the configuration confirmation message, can not be deciphered properly.
3GPP standard TS 25.331 V8.1.0 (the content of which is incorporated herein by reference) defines how this configuration should be performed in UTRAN (Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network).
The present invention aims to provide an alternative arrangement which will at least alleviate this problem.